Solid electrolytic capacitor with improved leakage current
A capacitor assembly that is capable of exhibiting good electrical properties even under a variety of conditions is provided. More particularly, the capacitor contains a capacitor element that includes a sintered porous anode body, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric. The solid electrolyte also contains a pre-coat layer that overlies the dielectric and includes an organometallic compound. A solid electrolyte overlies the pre-coat layer that includes pre-polymerized conductive polymer particles, and an external polymer coating overlies the solid electrolyte that contains a pre-polymerized particles and a cross-linking agent.
1. A capacitor assembly comprising a capacitor element, the capacitor element comprising;
a sintered porous anode body;
a dielectric that overlies the anode body;
a pre-coat layer that overlies the dielectric that includes an organometallic compound having the following general formula:
wherein,
M is an organometallic atom;
R 1 , R 2 , and R 3 are independently an alkyl or a hydroxyalkyl, wherein at least one of R 1 , R 2 , and R 3 is a hydroxyalkyl;
n is an integer from 0 to 8;
X is an organic or inorganic functional group;
a solid electrolyte that overlies the pre-coat layer, wherein the solid electrolyte contains pre-polymerized conductive polymer particles;
an external polymer coating that overlies the solid electrolyte and contains pre-polymerized conductive polymer particles and a cross-linking agent; and
wherein the capacitor assembly exhibits a leakage current of about 50 microamps or less alter being subjected to a rated voltage for 90 seconds.
2. The capacitor assembly of claim 1 , wherein the anode body includes tantalum and the dielectric includes tantalum pentoxide.
3. The capacitor assembly of claim 1 , wherein M is silicon.
4. The capacitor assembly of claim 3 , wherein the hydroxyalkyl is OCH 3 .
5. The capacitor assembly of claim 3 , wherein R 1 , R 2 , and R 3 are a hydroxyalkyl.
6. The capacitor assembly of claim 1 , wherein the organometallic compound is 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, glycidoxymethyl-tripropoxysilane, glycidoxymethyltributoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, β-glycidoxyethyl-tripropoxysilane, β-glycidoxyethyltributoxysilane, β-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, α-glycidoxyethyltripropoxysilane, α-glycidoxyethyltributoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyl-tripropoxysilane, γ-glycidoxypropyltributoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane, β-glycidoxypropyltripropoxysilane, α-glycidoxypropyltributoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane, α-glycidoxypropyltripropoxysilane, α-glycidoxypropyltributoxysilane, γ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltripropoxysilane, δ-glycidoxybutyltributoxysilane, δ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltripropoxysilane, γ-propoxybutyltributoxysilane, δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltripropoxysilane, α-glycidoxybutyltrimethoxysilane, α-glycidoxybutyltriethoxysilane, α-glycidoxybutyltripropoxysilane, α-glycidoxybutyltributoxysilane, or a combination thereof.
7. The capacitor assembly of claim 1 , wherein the solid electrolyte and external polymer coating are free of in situ polymerized conductive polymers.
8. The capacitor assembly of claim 1 , wherein at least one layer of the solid electrolyte is formed from a dispersion of particles that contain a polymeric counterion and an extrinsically conductive polymer, wherein the extrinsically conductive polymer is poly(3,4-ethylenedioxythiophene).
9. The capacitor assembly of claim 1 , wherein at least one layer of the solid electrolyte is formed from an intrinsically conductive polymer having repeating units of the following formula (I):
wherein,
R is (CH 2 ) a —O—(CH 2 ) b ;
a is from 0 to 10;
b is from 1 to 18;
Z is an anion;
X is a cation.
10. The capacitor assembly of claim 9 , wherein the intrinsically conductive polymer is poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butane-sulphonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-propanesulphonic acid, salt), or a combination thereof.
11. The capacitor assembly of claim 1 , wherein at least one layer of the solid electrolyte contains a hydroxyl-functional nonionic polymer.
12. The capacitor assembly of claim 1 , wherein at least a portion of the pre-polymerized conductive polymer particles in the solid electrolyte have an average size of from about 1 to about 80 nanometers.
13. The capacitor assembly of claim 12 , wherein at least a portion of the conductive polymer particles in the external polymer coating have an average size of from about 80 to about 500 nanometers.
14. The capacitor assembly of claim 1 , wherein at least one layer of the external polymer coating is formed from a dispersion of particles that contain a polymeric counterion and an extrinsically conductive polymer, wherein the extrinsically conductive polymer is poly(3,4-ethylenedioxythiophene).
15. The capacitor assembly of claim 14 , wherein the crosslinking agent is a diamine.
16. The capacitor assembly of claim 1 , further comprising an anode termination that is in electrical connection with the anode body;
a cathode termination that is in electrical connection with the solid electrolyte; and
a housing that encloses the capacitor element and leaves exposed at least a portion of the anode termination and the cathode termination.
17. The capacitor assembly of claim 16 , wherein the housing is formed from a resinous material that encapsulates the capacitor element.
18. The capacitor assembly of claim 16 , wherein the housing defines an interior cavity within which the capacitor element is positioned, wherein the interior cavity has a gaseous atmosphere that includes an inert gas.
19. The capacitor assembly of claim 1 , wherein the capacitor assembly exhibits a breakdown voltage of about 50 volts or more.
20. The capacitor assembly of claim 1 , wherein the capacitor assembly exhibits a leakage current of about 20 microamps or less after being subjected to a rated voltage for 180 seconds.
21. A capacitor assembly comprising a capacitor element, the capacitor element comprising;
a sintered porous anode body;
a dielectric that overlies the anode body;
a pre-coat layer that overlies the dielectric that includes an organometallic compound having the following general formula:
wherein,
M is an organometallic atom;
R 1 , R 2 , and R 3 are independently an alkyl or a hydroxyalkyl, wherein at least one of R 1 , R 2 , and R 3 is a hydroxyalkyl;
n is an integer from 0 to 8;
X is an organic or inorganic functional group;
a solid electrolyte that overlies the pre-coat layer, wherein the solid electrolyte contains pre-polymerized conductive polymer particles;
an external polymer coating that overlies the solid electrolyte and contains pre-polymerized conductive polymer particles and a cross-linking agent;
wherein the solid electrolyte and external polymer coating are free of in situ polymerized conductive polymers.
22. The capacitor assembly of claim 21 , wherein the anode body includes tantalum and the dielectric includes tantalum pentoxide.
23. The capacitor assembly of claim 21 , wherein M is silicon.
24. The capacitor assembly of claim 23 , wherein the hydroxyalkyl is OCH 3 .
25. The capacitor assembly of claim 23 , wherein R 1 , R 2 , and R 3 are a hydroxyalkyl.
26. The capacitor assembly of claim 21 , wherein the organometallic compound is 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, glycidoxymethyl-tripropoxysilane, glycidoxymethyltributoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, β-glycidoxyethyl-tripropoxysilane, β-glycidoxyethyltributoxysilane, β-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, α-glycidoxyethyltripropoxysilane, α-glycidoxyethyltributoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyl-tripropoxysilane, γ-glycidoxypropyltributoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane, β-glycidoxypropyltripropoxysilane, α-glycidoxypropyltributoxysilane, α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane, α-glycidoxypropyltripropoxysilane, α-glycidoxypropyltributoxysilane, γ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltripropoxysilane, δ-glycidoxybutyltributoxysilane, δ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltripropoxysilane, γ-propoxybutyltributoxysilane, δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, δ-glycidoxybutyltripropoxysilane, α-glycidoxybutyltrimethoxysilane, α-glycidoxybutyltriethoxysilane, α-glycidoxybutyltripropoxysilane, α-glycidoxybutyltributoxysilane, or a combination thereof.
27. The capacitor assembly of claim 21 , wherein at least one layer of the solid electrolyte is formed from a dispersion of particles that contain a polymeric counterion and an extrinsically conductive polymer, wherein the extrinsically conductive polymer is poly(3,4-ethylenedioxythiophene).
28. The capacitor assembly of claim 21 , wherein at least one layer of the solid electrolyte is formed from an intrinsically conductive polymer having repeating units of the following formula (I):
wherein,
R is (CH 2 ) a —O—(CH 2 ) b ;
a is from 0 to 10;
b is from 1 to 18;
Z is an anion;
X is a cation.
29. The capacitor assembly of claim 28 , wherein the intrinsically conductive polymer is poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butane-sulphonic acid, salt), poly(4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-propanesulphonic acid, salt), or a combination thereof.
30. The capacitor assembly of claim 21 , wherein at least one layer of the solid electrolyte contains a hydroxyl-functional nonionic polymer.
31. The capacitor assembly of claim 21 , wherein at least a portion of the pre-polymerized conductive polymer particles in the solid electrolyte have an average size of from about 1 to about 80 nanometers.
32. The capacitor assembly of claim 31 , wherein at least a portion of the conductive polymer particles in the external polymer coating have an average size of from about 80 to about 500 nanometers.
33. The capacitor assembly of claim 21 , wherein at least one layer of the external polymer coating is formed from a dispersion of particles that contain a polymeric counterion and an extrinsically conductive polymer, wherein the extrinsically conductive polymer is poly(3,4-ethylenedioxythiophene).
34. The capacitor assembly of claim 33 , wherein the crosslinking agent is a diamine.
35. The capacitor assembly of claim 21 , further comprising an anode termination that is in electrical connection with the anode body;
a cathode termination that is in electrical connection with the solid electrolyte; and
a housing that encloses the capacitor element and leaves exposed at least a portion of the anode termination and the cathode termination.
36. The capacitor assembly of claim 35 , wherein the housing is formed from a resinous material that encapsulates the capacitor element.
37. The capacitor assembly of claim 35 , wherein the housing defines an interior cavity within which the capacitor element is positioned, wherein the interior cavity has a gaseous atmosphere that includes an inert gas.
38. The capacitor assembly of claim 21 , wherein the capacitor assembly exhibits a breakdown voltage of about 50 volts or more.
39. The capacitor assembly of claim 21 , wherein the capacitor assembly exhibits a leakage current of about 50 microamps or less after being subjected to a rated voltage for 90 seconds.
40. The capacitor assembly of claim 21 , wherein the capacitor assembly exhibits a leakage current of about 20 microamps or less after being subjected to a rated voltage for 180 seconds.